The present invention relates to an improved light emitting diode display with PCB (printed circuit board) base, and more particularly to a LED display with higher luminous intensity, greater heat-dispersing area, increased stability of the forward voltage and wave length (color) of the LED and decreased light output degradation and prolonged operating lifespan.
At present, all the developed countries of the world positively research and develop photoelectric materials. However, respecting the packaging technique of LED lamps, there have been relatively few advances.
Among the conventional packaging techniques, there is one type of packaging procedure wherein the diodes are first attached to lead frames and then encapsulated in epoxy to form bulb-like LED lamps. Because bowl-shaped reflector surfaces are formed on the die attach zones of the lead frame, higher luminous intensity can be achieved. The LED lamps can be arranged and soldered on a circuit board to form a display. However, such display is manufactured at high cost and the luminous intensity and color of the LED lamps are not so easily matched with each other. Another kind of display applies conductive epoxy to attach the LED to the PCB and applies conductive wires to connect the cathode and anode. Then, a reflector cover is added to complete the display. In such display, because the reflector cover is made from plastic and clearance exists between the PCB and reflector cover, the light reflecting and concentrating effect thereof is much poorer than that of the bowl-shaped reflector surfaces of the lead frame. Therefore, the luminous intensity of such display is lower. Moreover, because the basic material of the PCB is fiber glass with epoxy, the heat-conducting effect is poor and the heat conduction is limited within a small range of copper foil of the front surface of the PCB so that when the LED is powered on, the accompanying heat is difficult to disperse and thus the forward voltage and wave length (color) is not so stable and the illumination is reduced. Also, the lamp life is shortened.